Brake boosters of this type are widespread and are generally attached to a vehicle body part—usually the splash wall—in the engine compartment of a vehicle by means of two or more connecting bolts. For efficient mounting, the connecting elements are secured on or in the housing of the brake booster. During the mounting of the brake booster, the above-mentioned connecting elements are plugged through corresponding breakthroughs in the vehicle body part and are secured from the opposite side.
A strong, axially acting compression spring—the restoring spring—is fastened in the interior of the booster housing of brake boosters of the generic type. In a brake booster which is not yet mounted in the vehicle, the spring force brings about slight elastic deformation of the booster housing, and in the process the connecting elements which were originally arranged parallel to one another are spread apart. This can lead to mounting problems, because the corresponding pattern of holes on the splash wall no longer fits in an optimum way.
In order to counteract the problem with the spread-apart connecting bolts during mounting, it is known to attach, in the region of the bearing surface in the interior of the booster housing, additional, separate reinforcement components which avoid or reduce the tendency to spread apart. In such solutions, the greater system weight, the costly manufacture and the mounting with a large number of process offsets and therefore the higher costs are considered to be disadvantageous.
US 2012/0304849 A1, which is incorporated by reference, discloses a different approach to a solution in which the planar bearing surface on the rear side of the booster housing is configured in a star shape with 8 rounded arms which extend, at their radial outer edge, into the rest of the rear wall of the booster housing, which is correspondingly configured in a corrugated fashion in the circumferential direction. Although such a structure does not require additional parts, it brings about a massive undesired increase in the “dead volume” in the working chamber—the space between the rear wall and the movable wall in the interior of the housing. This worsens the response behaviour of the brake booster and more air has to be evacuated after each braking process.